A blockchain network simulator SimBlock was developed to enable large-scale blockchain researches. Since it was released in June 2019, it has facilitated number of studies on blockchain performance and security. We demonstrate how such a simulator enables blockchain studies by showing experiments running on SimBlock.

Forks in a blockchain sacrifice security. In this paper, we propose a protocol for quickly propagating block generation notifications in the blockchain network quickly to reduce the fork rate. Block generation notifications contain a Bloom filter that represents transactions in the generated block. Thus, when nodes receive a block generation notification, they can start mining the next block. In experiments in which a simulator is used, we compared the propagation time of a block generation notification with that of a block in the existing protocol. As a result, the propagation time of the 50 %ile is 41.1 % of an existing protocol, the 90 %ile is 39.2 % of the existing protocol, and the fork rate calculated from the average propagation time is 40.8 % of the existing protocol.

In a public blockchain, the block propagation time has a significant impact on the performance, security and fairness of mining. Reducing the propagation time can increase the transaction processing performance, reduce the fork rate, and increase security. We propose a method to improve block propagation with block sender switchover, even if a node is receiving a block. The method is not vulnerable to eclipse attacks because the neighboring nodes are not changed. Our simulation shows that the proposed method improves the 90th percentile value of the propagation time by up to 18% and the fork rate by up to 7.9%.